The pressure adjustment (in my Office Control) is a white plastic screw inside a brass three-way fitting on the outlet of the vibe pump (red plastic inside a metal holder).

It's about a 1/4" screw with a very fine slot - most screwdrivers wide enough to fit across will have a blade too thick to fit in the slot. You may want to file down a cheap stubby slot screwdriver for adjustments.

My "shipped" pressure was almost 14 bar (measured with a portafilter gauge). I have turned it down to 10 (about 1.5 turns counterclockwise) and will report on the results later.

I also followed the suggestion to reroute the overflow back to the reservoir as I live in a very hard water area and use Volvic bottled water in the machine. Supposedly Volvic is soft enough to minimize scaling problems.

When I tried to adjust the pressure down on my Quickmill Eliane, I found I had to back the threads almost to the point where where the fitting came off. I removed the nut and spring and and filed down the end of the spring, probably less than a mm. I was then able to get the desired pressure (9.5) without risking the screw falling off. I agree that the adjustment is non-linear. Originally mine was up at about 16!Russell

Posted Fri Jul 6, 2012, 7:45am Subject: Where is the OPV on a Grimac Mia ELE?

]]Hello. Sorry to revive an old thread.

I got to reading about brew pressures and HX machines, and found this thread.

I have a Grimac Mia Electronic version. I decided to open the machine to try the OPV volume runoff method of "estimating" brew pressure. I locked a blind PF and turned on the brew button. The pump came on, after 6-8 sec, the pump became quiet as it labored through the blind PF, the beeping - with a flashing light from the brew button. After 20-25 sec of this beeping, I decided to turn the brew button off. I did NOT see water coming out of the return to tank hose. From the readings, it was mentioned that if little (<2oz/25-30sec) or NO water comes out, then the OPV was adjusted high from the factory.

I looked for the OPV, taking note of the pics of the different OPVs of different machines. I found a pic from the La Valentina - a Grimac Machine, I believe, and used this as a guide to identifying mine. I followed the outflow tube, and the tube was attached to this:

Instead of just a barrel, several fittings are seen attached to a brass block. The outflow tubing attaches to this block as well. I don't see the nut I need to adjust to release pressure. Behind the block, in this pic, is a sort of switch. Maybe a pressure sensor that sets off the beeping when pump pressure is exceeded?

It's beginning to sound like the dream machine not only has perfect temp stability with the ability to set a desired temp but also a controled ramp down of extraction pressure. Also with the ability to set a pressure profile.

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